Homemade Grout Cleaner That Won't Wreck Your Grout

Dirty grout makes a clean bathroom look dirty. You can mop a tile floor until it shines and those dark lines still make it look neglected. It's also one of the easiest things to damage by trying too hard, with harsh acids, wire brushes or a different strong cleaner every week.

Use these at your own risk, and test a small hidden spot first. Grout colors and sealers vary a lot, and a homemade paste doesn't come with a label.

What grout actually is

Most grout in DFW homes is cement-based. The IICRC compares it to a concrete driveway or sidewalk. It's porous, it soaks up spills and mop water, and it stains easily if it isn't sealed and kept up.

That matters for cleaning. The IICRC says acidic or alkaline cleaners can wear down grout and its sealer over time and leave residue that pulls in more dirt. Its advice for routine floor care is a no-rinse, neutral pH cleaner. The pastes below are for occasional deep cleaning. They're not meant for every mop day.

Recipe 1, the gentle paste

Baking soda and water. Stir a little water into half a cup of baking soda until it's like toothpaste. Brush it into the grout lines, scrub, and rinse well.

This handles everyday grime, soap film along shower lines and the gray traffic path in front of the kitchen sink. It's mild, so it's the one to start with.

Recipe 2, the stain paste

For yellowed or stained lines, swap the water for drugstore hydrogen peroxide, the 3% kind in the brown bottle. A common ratio is about 2 parts baking soda to 1 part peroxide. Mix it in an open bowl, right before you use it.

1. Sweep or vacuum first. For a shower, rinse the walls.
2. Test on a hidden grout line, like behind the toilet or inside a closet. Wait 10 minutes, rinse and look. Peroxide is a mild bleaching agent and can lighten colored grout.
3. Spread the paste along the lines with a grout brush or an old toothbrush.
4. Let it sit about 10 minutes.
5. Scrub along the line, not across the tile.
6. Rinse with plenty of clean water and dry with a towel.

Toss what's left. Don't save mixed paste in a closed jar. Poison Control says hydrogen peroxide should stay in its original opaque bottle, and once it's opened it only stays strong for a few months. Keep the bottle capped and stored with your other cleaners.

Natural stone tile

If your tile is marble, travertine or limestone, skip the baking soda paste. The Natural Stone Institute warns that scouring powders and creams often contain abrasives that may scratch some stones, and that acids can dull or etch them. Use a neutral cleaner, stone soap or mild dish soap in warm water instead.

Newer porcelain tile

The IICRC says many porcelain tiles made since 2018, especially wood-look and stone-look styles, can be damaged by alkaline cleaners. Baking soda is mildly alkaline. On those floors, test carefully and keep it to spot work.

When it's mildew, not dirt

Dark spots in shower corners and along the tub are often mildew. Mildew grows back if you only scrub off the surface. A bleach solution or a store mildew remover is the usual tool here, and that's where you have to be careful.

NMSU's extension guide suggests 1/2 cup bleach in 1 cup water for mildew on grout, left on for 5 minutes and then rinsed with clear water. CDC's bleach safety page says to wear gloves and eye protection, open windows and doors, and never mix bleach with ammonia or any other cleaner. If you used the peroxide paste or any vinegar spray earlier, rinse the area very well and let it dry before bleach goes anywhere near it.

After that, keep the shower drier. Run the exhaust fan during and after showers, and leave the door or curtain open so it can air out.

The never-mix rules

• Bleach and ammonia make chloramine gas.
• Bleach and vinegar, or any acid, make chlorine gas. Some toilet bowl and tile cleaners are acidic, so read labels.
• Hydrogen peroxide and vinegar in the same bottle form peracetic acid. The Missouri Poison Center describes it as corrosive to skin, eyes and the airways.

One cleaner at a time. Rinse between them. If anyone feels their eyes or throat burning, get them to fresh air and call Poison Help at 1-800-222-1222.

When cleaning isn't enough

Sometimes grout is just stained through. The IICRC says deeply set stains may need regrouting, or a color seal product that covers the old color. Cracked or crumbling grout is a repair job, not a cleaning job.

Once your grout is clean and completely dry, a penetrating sealer helps it resist the next spill. The IICRC recommends sealing grout after a professional cleaning. Follow the sealer's label for drying time and ventilation, and keep pets off the floor until it's done.

Sources

1. Consumer Floor and Furnishings Care Information, tile, stone and grout (IICRC tip sheet) (accessed Oct 8, 2026)
2. Is hydrogen peroxide safe? (Poison Control, National Capital Poison Center) (accessed Oct 8, 2026)
3. Some Things Just Don't Mix (Missouri Poison Center, updated Jul 7, 2025) (accessed Oct 8, 2026)
4. Chlorine gas, what happens if you mix bleach and other cleaners (Poison Control, National Capital Poison Center) (accessed Oct 8, 2026)
5. How to Safely Clean and Sanitize with Bleach (CDC) (accessed Oct 8, 2026)
6. Green Cleaning Methods for Your Home, Guide G-315 (New Mexico State University Extension, revised Jan 2019) (accessed Oct 8, 2026)
7. Learn About Cleaning Products for Natural Stone (Natural Stone Institute) (accessed Oct 8, 2026)